The use of concrete median barriers between opposing lanes of interstate highways and along other roadways has been a major advancement in the reduction of head-on collisions and other accidents between approaching vehicles on the roadways. The Type 50 concrete barrier is primarily used because of its inclined lower surface on each side of the barrier adjacent the roadway for straightening a front vehicle wheel which rides up on the barrier when the vehicle accidentally approaches the barrier at a small angle of incidence. However, when a vehicle impacts the concrete barrier at a high angle of incidence, the high friction hard surface of the concrete barrier and the higher impact force commonly result in significantly greater damage to the vehicle and to the barrier as well as greater injuries to the vehicle driver and passengers in the vehicle. In fact, some impacts will either crack the concrete barrier and/or cause the vehicle to spin out of control, sometimes resulting in accidents with other vehicles moving on the roadway.
There have been several systems proposed or used for reducing the damages to motor vehicles and injuries to their occupants when the vehicles accidentally impact the concrete median barriers. One system is known as the PEDS Barrier which has been used along vehicle race tracks and incorporates a continuous series of vertical cylinders. Each cylinder has a diameter of about 16" and is constructed of a high density polyethylene. The cylinders are positioned adjacent the concrete wall or barrier and are covered by an overlapping sheet of high density polyethylene material. The cylinders are secured to the barrier by longitudinally spaced cables extending around the barrier, and the sheet is attached by bolts to the cylinders. The cost of this system is substantial and is therefore primarily used on concrete walls or barriers at race tracks adjacent the seating area for patrons.
U.S. Pat. Nos. 4,681,302 and 5,054,954 disclose other forms of energy absorbing roadway barriers which involve formed or molded sheets or bodies of plastics material to form a container defining a chamber. The chamber is filled with a liquid or a filler material which can absorb impact forces, sometimes by being forced out of the container when the container is crushed by an impacting vehicle.
With any such form of energy absorbing or dissipating system which is constructed to form or modify highway median barriers, it is highly desirable for the system to be of economical construction and to be easily and quickly installed along the highway or on an existing concrete barrier so that disruption of traffic on the adjacent roadway lane is minimized. It has also been found desirable for the device to dissipate or distribute the energy of an impacting vehicle and to minimize the friction between the device and the vehicle and guide the vehicle so that the vehicle is redirected back into the adjacent traffic lane with a minimum loss of speed in order to reduce vehicle accidents and injuries to occupant in the vehicles. It is further desirable for the energy dissipating system or device to withstand impacts at high angles of incidence and from high speed vehicles without damaging the device or the concrete barrier so that maintenance on the barrier and device is minimized.